Stimulation of the methylcoenzyme M reduction by uridine-5'-diphospho-sugars in cell-free extracts of Methanobacterium thermoautotrophicum (strain delta H).

J T Keltjens, H J Kraft, W G Damen, C van der Drift, G D Vogels

Index: Eur. J. Biochem. 184 , 395, (1989)

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Abstract

The hydrogen-dependent reduction of methylcoenzyme M catalyzed by coenzyme-depleted cell-free extracts of Methanobacterium thermoautotrophicum was stimulated by micromolar concentrations of a UDP-disaccharide present in the organism. The compound was isolated and identified as UDP-1-O-alpha-D-2-acetamido-2-deoxyglucopyranose (UDPGlcpNAc) glycosidically linked to 2-acetamido-2-deoxymannopyranosyluronic acid. Maximal stimulation was observed when both the UDP-disaccharide and mercaptoheptanoylthreonine phosphate were present in the reaction mixtures. The UDP derivative isolated was not specific in its action: other UDP-sugars tested in micromolar concentrations stimulated the methylcoenzyme M reduction to the same extent. The activated sugars presumably substitute for ATP, which is usually required in much higher concentrations to activate the methylcoenzyme M reductase system.